Telkoms terrible service

I have been having endless problems with Telkom. I overpaid my account by accident and is struggling for over a month for a refund. They asked me to email them my bank account details and ID and twice thereafter they close the query and does not refund me. I requested them to call me back and all they do is give me missed calls. This is rediculous. I have never had such poor service in my life be3